Generally, the image sharpness of photographic light-sensitive materials is reduced by increasing the thickness of the emulsion layer because of light scattering by silver halide emulsion grains. Particularly, in multilayer color light-sensitive materials having red-sensitive, green-sensitive and blue-sensitive emulsion layers, light scattering is increased because of the multilayer structure thereof, and reduction of sharpness becomes particularly in the emulsion layer of the lower layer.
U.S. Pat. No. 3,402,046 has disclosed a process for improving sharpness wherein coarse grains having a particle size of 0.7 micron or more which cause less light scattering are used in the blue-sensitive emulsion layer of the uppermost emulsion layer in the multilayer multicolor light-sensitive material.
U.S. Pat. No. 3,658,536 has disclosed a process for improving sharpness wherein one of two blue-sensitive emulsion layers is placed below the green-sensitive emulsion layer or the red-sensitive emulsion layer.
However, these processes have the disadvantage that graininess of the blue-sensitive emulsion layer is increased because of using coarse grains having a larger particle size than that required as the blue-sensitive emulsion grains.
U.S. Pat. No. 4,439,520 has disclosed a color photographic light-sensitive material having improved sharpness, sensitivity and graininess, wherein tabular silver halide grains having a thickness of less than 0.3 micron, a diameter of at least 0.6 micron and a ratio of diameter/thickness (aspect ratio) of 8:1 or more are used in at least one of the green-sensitive emulsion layer and the red-sensitive emulsion layer.
Such a process using tabular silver halide grains for the color photographic light-sensitive materials is excellent from the viewpoint of improving sharpness, sensitivity and graininess, but it is not always satisfactory to use tabular silver halide grains for color reversal light-sensitive materials.
Generally, processing of color reversal light-sensitive materials is carried out by the following steps: black-and-white development (first development).fwdarw.stopping.fwdarw.water wash.fwdarw.reversing.fwdarw.water wash.fwdarw.color development.fwdarw.stopping.fwdarw.water wash.fwdarw.conditioning bath.fwdarw.water wash.fwdarw.bleaching.fwdarw.fixation.fwdarw.water wash.fwdarw.drying. The first developing solution in these steps contains a silver halide solvent such as KSCN, Na.sub.2 SO.sub.3, etc. to provide a development acceleration effect by solution physical development. Therefore, in the first development processing step, dissolution of unexposed silver halide grains proceeds to some degree simultaneously with development of exposed silver halide grains, whereby solution physical development is carried out by means of developed silver or colloidal silver in the yellow filter layer.
Silver halide grains remaining without dissolution after the first development are fogged in the reversal bath and contribute to color development. Therefore, when solubility of silver halide grains is high, their contribution in color development is reduced and color density is sometimes reduced. Though silver halide grains generally have a certain distribution of particle size, grains having a comparatively smaller particle size disappear by dissolution when the solubility of silver halide grains is high. Therefore, graininess is increased, because only grains having a large particle size contribute to color development.
Tabular silver halide emulsion grains generally have higher solubility than spherical silver halide grains, because the shape is tabular. Therefore, it is very disadvantageous in practical application to use tabular silver halide grains for color reversal light-sensitive materials because of the above described reason.